Longtime Allegiant Air CEO Maury Gallagher will step down on June 1.
Allegiant president John Redmond will succeed Gallagher, who will continue as executive chairman.
As president, Redmond has had responsibility for all commercial and operational aspects of the company.
"As a 15-year Allegiant board member and president of the company since 2016, no one understands the vision and strategic direction of Allegiant better than John," Gallagher said in a prepared statement on Monday. "In truth, John's promotion to CEO and my step to executive chairman simply formalizes title changes that have been working in practice for the last several years."
Gallagher's departure will be the third retirement by a CEO of a top-10 U.S. carrier this year. Southwest CEO Gary Kelly stepped down at the end of January and American Airlines CEO Doug Parker will retire at the end of March.
When Gallagher took charge of Allegiant in 2001, the carrier was emerging from bankruptcy and had just one plane. The Las Vegas-based discount airline now has more 110 aircraft and a broad network of more than 130 U.S. cities.
Allegiant has also earned a reputation for returning some of the highest operating margins in the global airline industry.
Coming out of the pandemic, Allegiant is once again growing quickly. The carrier will soon add Boeing 737 Max planes to what is now an all-Airbus fleet and is pursuing a joint venture with Mexico's Viva Aerobus.
Redmond first joined the Allegiant board in 2007.